The invention relates to a safety device to prevent accidental unwinding of a rolling shutter or rolling overhead door that is wound on a shaft, having a cogwheel which is corotational with the winding shaft and has recesses uniformly distributed about the circumference for receiving radially movable tumblers, with a cage which surrounds the cogwheel and has an abutment in the form of a recess for engagement by the tumblers that are raised by centrifugal force, and with a fixedly disposed housing against which the cage can be turned with friction with the consumption of energy.
A safety device of the kind described is disclosed in German Patent No. 31 40 792. A disadvantage in this known device is that it is relatively expensive to manufacture. The cage has both on its inside and on its outside recesses which require special machining. Also the housing consists of three parts of which the middle part consists of a thick steel plate which has to be cut out in an expensive manner by means of a cutting torch and then finished. Lastly, it must be considered as a disadvantage that, with this apparatus, a severe collision of the cage against the housing can occur in the event of actuation, which can result in damage to the apparatus and/or to the shutter or door.
The problem therefore poses itself of creating a safety device of the kind described above, which will avoid the disadvantages mentioned and which especially can be manufactured more simply and thus less expensively, and which will assure a gentle but secure braking of the winding shaft in case of actuation.